关于2024 如何在 IntelliJ IDEA 2023 中开发 Java 8 Springboot 2.x 的项目
2024-06-06
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## 前言
<br>
众所周知 `IntelliJ IDEA 2023.2` 新建 `springboot` 项目时，只能新建 `springboot 3.x`，并且只支持 `JDK17` 以上版本
<br>
虽然我并不是祖宗之法不可变的保守派，但我非常偶尔的时候也会遇到需要开发一个 `JDK8` `Srpingboot 2.x` 的需求，IDEA 这样一刀切，逼得我只能自己手动新建项目了
<br>
其实最早在学Java的时候，新建项目都是普通的本地项目，自己加jar包依赖，自己写配置文件的，后来有了maven，就可以快速引入依赖，并且自动解决依赖链的问题。后来有了Springboot，配置文件也可以不写少写。现在无非就是退回去，新建一个Maven项目，然后手动配置Springboot的部分。
<br><br>
## 折腾
<br>
1. 新建Maven项目
JDK选择1.8
Archetype选择quickstart
<br>
2. 根据自己习惯 改变src下的目录结构
如图我删了test目录
新建了resources 并且在Project Structure中配置为Resources类型
<br>
附上一个好看的banner.txt
```txt
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```
<br>
3. 配置一下maven
这里加了
springboot redis 开发环境中的tomcat mysql mybatisplus lombok apache工具箱等基础依赖
底部加了阿里云镜像maven加快速度
整体打war包，生产环境需要通过tomcat执行
版本选择截止今天最后一个springboot 2的版本 2.7.18
<br>
`pom.xml`
```xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.zzzmh</groupId>
<artifactId>spring-boot-demo</artifactId>
<packaging>war</packaging>
<version>1.0.0</version>
<name>spring-boot-demo</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.18</version>
</parent>
<properties>
<java.version>1.8</java.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<version>8.4.0</version>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.6</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.15</version>
</dependency>
<dependency>
<groupId>com.alibaba.fastjson2</groupId>
<artifactId>fastjson2</artifactId>
<version>2.0.33</version>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
<!-- 阿里云maven仓库 -->
<repositories>
<repository>
<id>public</id>
<name>aliyun nexus</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>public</id>
<name>aliyun nexus</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>
```
<br>
改完以后刷新一下maven依赖
<br>
4. 新建启动类
参考前文，我这里选择war包，所以启动类是按照war方式建
删除原本的 `App.java` 在同级新建2个启动类文件
<br>
`SpringBootDemoApplication.java`
```java
package com.zzzmh;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootDemoApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootDemoApplication.class, args);
}
}
```
<br>
`ServletInitializer.java`
```java
package com.zzzmh;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(SpringBootDemoApplication.class);
}
}
```
<br>
如果到这一步都配置正确，已经可以执行 `SpringBootDemoApplication` 的 `main` 方法启动试试看了，因为springboot 有默认配置，无配置文件也可以启动
<br>
启动后看到这样的控制台输出就说明启动成功了
```java
2024-06-06 12:03:29.902 INFO 17412 --- [ main] com.zzzmh.SpringBootDemoApplication : Starting SpringBootDemoApplication using Java 1.8.0_345 on ROG-G14 with PID 17412 (C:\mywork\idea-2023-workspace\spring-boot-demo\target\classes started by Administrator in C:\mywork\idea-2023-workspace\spring-boot-demo)
2024-06-06 12:03:29.905 INFO 17412 --- [ main] com.zzzmh.SpringBootDemoApplication : The following 1 profile is active: "light-dev"
2024-06-06 12:03:30.557 INFO 17412 --- [ main] .s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode
2024-06-06 12:03:30.562 INFO 17412 --- [ main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data Redis repositories in DEFAULT mode.
2024-06-06 12:03:30.580 INFO 17412 --- [ main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 6 ms. Found 0 Redis repository interfaces.
2024-06-06 12:03:30.683 WARN 17412 --- [ main] o.m.s.mapper.ClassPathMapperScanner : No MyBatis mapper was found in '[com.zzzmh]' package. Please check your configuration.
2024-06-06 12:03:31.096 INFO 17412 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2024-06-06 12:03:31.102 INFO 17412 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2024-06-06 12:03:31.103 INFO 17412 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.83]
2024-06-06 12:03:31.269 INFO 17412 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2024-06-06 12:03:31.269 INFO 17412 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1323 ms
2024-06-06 12:03:31.542 WARN 17412 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Failed to determine a suitable driver class
2024-06-06 12:03:31.545 INFO 17412 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2024-06-06 12:03:31.557 INFO 17412 --- [ main] ConditionEvaluationReportLoggingListener :
```
<br>
后面有一个这样的报错是正常的，因为还没配置JDBC的参数
```java
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2024-06-06 12:03:31.575 ERROR 17412 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
Reason: Failed to determine a suitable driver class
Action:
Consider the following:
If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (the profiles light-dev are currently active).
```
<br>
相信能看到这里的人，应该都能自己写springboot的参数配置文件
这里只列举一个最简单基础的配置吧
开发环境一切从简就行，把数据库 用户名密码 还有 service目录改成你自己的 就OK了
<br>
`application.yml`
```yml
# 通用配置
spring:
profiles:
active: dev
mvc:
pathmatch:
matching-strategy: ant_path_matcher
```
<br>
`application-dev.yml`
```yml
# 开发环境
server:
port: 8080
servlet:
context-path: /demo
spring:
redis:
host: 127.0.0.1
port: 6379
servlet:
multipart:
max-file-size: 100MB
max-request-size: 100MB
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/xxx?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&tinyInt1isBit=false&allowPublicKeyRetrieval=true
username: xxxxxx
password: xxxxxx
mybatis-plus:
mapper-locations: classpath*:/mapper/*.xml
type-aliases-package: com.zzzmh.service
global-config:
db-config:
id-type: auto
logic-delete-value: 1
logic-not-delete-value: 0
insert-strategy: not_null
update-strategy: not_null
banner: false
configuration:
map-underscore-to-camel-case: true
cache-enabled: true
call-setters-on-nulls: true
logging:
level:
org.springframework.web: trace
org.mybatis: trace
```
<br><br>
## END
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